Therapeutic Plasma Exchange in Multiple Sclerosis Patients with Abolished Interferon-beta Bioavailability.

ABSTRACT

BACKGROUND: Neutralizing antibodies (NAb) to interferon-beta (IFN-ß) are associated with reduced bioactivity and efficacy of IFN-ß in multiple sclerosis (MS). The myxovirus resistance protein A (MxA) gene expression is one of the most appropriate markers of biological activity of exogenous IFN-ß. We hypothesized that therapeutic plasma exchange (TPE) can restore the ability of IFN-ß to induce the MxA mRNA expression and that maintenance plasmapheresis can sustain the bioavailability of IFN-ß. MATERIAL AND METHODS: Eligible patients underwent 4 primary separate plasma exchange sessions. After the induction TPE sessions, they were transferred to maintenance plasmapheresis. Bioactivity of IFN-ß was expressed as in vivo MxA mRNA induction in whole blood using RT-qPCR. RESULTS: Six patients with low IFN-ß bioavailability detected by the MxA mRNA response were included. Four patients became biological responders after induction plasmapheresis. In 2 patients an increase of MxA mRNA expression was found, but the values persisted below the cut-off and the patients remained as "poor biological responders". The effect of maintenance plasmapheresis was transient MxA mRNA expression values reverted to the baseline levels after 1-2 months. CONCLUSIONS: Therapeutic plasma exchange is able to restore the bioavailability of IFN-ß in the majority of studied patients, but the effect of TPE on the IFN-ß bioavailability was transient.